This invention is in the field of surgery. More particularly, it relates to a tissue approximation device. By xe2x80x9capproximationxe2x80x9d we mean to include variously the specific movement of two regions of tissue towards each other, the movement of one or more selected tissue regions or areas, the maintenance and/or fixation of one or more selected tissue regions in a selected position, and the maintenance and/or fixation of a selected area of tissue against shape variation due to tissue xe2x80x9cspringiness.xe2x80x9d We will also refer to these functions as xe2x80x9cstabilizationxe2x80x9d of a tissue region. For instance, the inventive device may be used to facilitate wound healing by holding soft tissue together under improved distribution of tension and with minimal disruption of the wound interface and its nutrient supplies. Generally, the device has multiple sites for grasping said tissue using tines or prongs or other generally sharp, projecting points, extending from and preferably affixed to a single, supportive backing. Various processes of using the inventive device are also a portion of the invention.
The inventive device is preferably used for the approximation, mobilization, or fixation of tissue. As noted above, these terms are meant variously to include the specific movement of two regions of tissue towards each other, the movement of one or more selected tissue regions or areas, the maintenance of one or more selected tissue regions in a selected position, and the maintenance of a selected area of tissue against shape variation due to tissue xe2x80x9cspringiness.xe2x80x9d Using our inventive device, a variety of approximation procedures may be achieved, variously from the movement of two tissue areas towards each other at a common wound margin to the maintenance of an area of tissue in a specific position during or after a surgical procedure, e.g. brow lifts or ACL regions.
For instance, our inventive device allows healing of soft tissue due to its maintenance of tissue position. The surgically induced healing of soft tissue wounds involves two phases, the mechanical phase of wound closure followed by the biochemical phase which involves protein bridging and scarring. In the mechanical phase, the edges of soft tissue are held in contact by essentially two components: 1) The physical properties and device-tissue interactions of the materials holding the tissue edges in contact, e.g. sutures or staples; and 2) An early deposition of proteinaceous material that has adhesive characteristics, e.g. fibrin glue.
Only in the biochemical phase, which occurs after the mechanical phase, do tissue components replace the mechanical components adhering the wound surfaces. During the biochemical phase, the inflammatory cascade generates signals which induce fibroblasts to migrate into the wound and synthesize collagen fibers.
Collagen is the primary constituent of connective tissue and ultimately determines the pliability and tensile strength of the healing wound. Tensile strength is gradually recovered; 60% of ultimate wound strength is achieved after approximately 3 months. However, this process is successful only if the previous mechanical phase has proceeded normally.
The surgeon""s goal is to optimize the strength and often the cosmetic appearance of a wound closure or tissue coaptation. For this to happen, tissue is mechanically approximated until the wound has healed enough to withstand stress without artificial support. Optimal healing requires the application of appropriate tissue tension on the closure to eliminate dead space but not create ischemia within the tissue. Both of these circumstances increase the risk of wound infection and wound dehiscence.
Although the biomaterial composition of sutures has progressed considerably, the sophistication of manual suture placement in wounds has advanced relatively little since the original use of fabrics several thousand years ago to tie wound edges together. The wide tolerance ranges for suture placement, tension, and configurations, both amongst different surgeons and for different implementations by the same surgeon, result in a significant component of sub-optimal technique. Yet, the technique used for wound closure forms the foundation for all subsequent events in the healing process. It is during this mechanical phase that tissue tension is high, edema and inflammation are intense, wound edge ischemia is greatest, and that one can already observe the complication of wound failure.
Soft tissue is well known for its inability to hold tension. Even when optimally placed, sutures gradually tear through soft tissue, producing gaps in wounds and possibly leading to the eventual failure or sub-optimization of wound healing. Furthermore, since sutures require the implementation of high levels of tension to counteract the forces acting to separate tissues, they may strangulate the blood supply of the tissues through which they are placed, thus inhibiting the delivery of wound nutrients and oxygen necessary for healing.
There have been many attempts to construct wound closure devices that decrease closure time and improve cosmesis. U.S. Pat. Nos. 2,421,193 and 2,472,009 to Gardner; U.S. Pat. No. 4,430,998 to Harvey et al.; U.S. Pat. No. 4,535,772 to Sheehan; U.S. Pat. No. 4,865,026 to Barrett; U.S. Pat. No. 5,179,964 to Cook; and U.S. Pat. No. 5,531,760 to Alwafaie suggest such devices. However, these devices are not useful in surgical or deeper wounds. They only approximate the skin surface, joining skin edges variously through external approaches, using adhesives or nonabsorbable attachment points that penetrate tissue. The devices minimally improve the biomechanics of wound closure, and do not adequately approximate the deeper layers of the closure, i.e. fascia or dermis. Externally placed attachment points that puncture the skin lateral to the wound also interfere with long-term cosmesis and provide a possible conduit for infecting micro-organisms.
U.S. Pat. No. 5,176,692 to Wilk et al., discloses a device for hernia repair that utilizes mesh with pin-like projections to cover hernia defects. This device, however, is used in a laparoscopic hernia repair in conjunction with an inflatable balloon. Closure devices for deeper tissues are described in U.S. Pat. Nos. 4,610,250 to Green; U.S. Pat. No. 5,584,859 to Brozt et al.; and U.S. Pat. No. 4,259,959 to Walker. However, these devices either work in conjunction with sutures, are made of materials that do not suggest biodegradability, or are designed in such a way as not to impart uniform tension on the closure, increasing the risk of wound separation and failure of wound healing.
The present invention is a biodegradable tissue approximation device. The device includes a plurality of attachment points, e.g. tines, prongs, or other generally sharp or blunt parts, connected to a backing that can be manipulated to close wounds, join soft tissue or bone, or create anastomoses. This multi-point tension distribution system (MTDS) device may be placed with minimal tissue trauma. The present invention typically incorporates the deeper layers of tissue within the closure, and the multiple attachment points distribute the resulting tension, often uniformly. Approximation from the internal aspect of the wound minimizes the potential for dead space in the closure, thus decreasing the risk of sub-optimal healing. Moreover, because the device is absorbed, a second procedure is not typically needed to remove the device.
Thus, the present invention improves the mechanical phase of healing by facilitating wound closure and/or the coaptation of tissues prior to initiation of the biochemical phase of wound healing. Placement of the device maximizes the chance for a good cosmetic result and is not heavily dependent on surgeon skill. Closure time is also shortened, decreasing overall cost and risk of operative complications.
The present invention is a device that improves the mechanical phase of wound healing. In the preferred embodiment, tissue edges are stabilized by a plurality of attachment points that extend from and are affixed to a supportive backing. The density, shape, length, and orientation of attachment points on the backing may be varied to suit the procedure, type of tissue being approximated, and/or area of the body involved. The flexibility of the backing is also variable and dependent on the materials used and dimensions of the backing. In function, the forces or tension placed upon the tissues by the inventive device are mirrored in the backing of the device. Said another way, the shape of the tines relay any forces to the backing of the device. The backing is generally in shear along its length. In the preferred embodiment, the device is biodegradable, and the attachment points uniformly distribute tension over the contact area between the device and tissue.
Processes of using the present invention are also provided. The device may be used to close wounds and create vascular anastomoses. The. device may also be manipulated to approximate soft tissue and soft tissue to bone. The device may be used to mobilize, move, or stabilize a selected region or area of tissue, as noted above.
A further application may include approximation of soft tissue in brow lift and other craniofacial and maxillofacial surgical procedures. Such a device may be optimized to distribute loads over the device while the device remains attached to the patient""s cranium. The brow lift device may further include multiple variations of the device and is preferably biodegradable and absorbable by the patient. The device may also be made from biological materials. A device variation may be installed into a patient by first creating an incision in the patient""s scalp. This incision is preferably a predetermined length corresponding to the length of scalp or tissue desired to be lifted. At one end of the incision, preferably the end farthest away from the scalp or tissue to be lifted, the doctor or surgeon would drill a hole into the cranium. At the opposing end of the incision, the device may be inserted under the scalp or tissue which is then set on the device via attachment points affixed to the device surface. The surgeon may then lift the scalp or tissue via the device, which may then be secured to the cranium by inserting an anchoring post into the drilled hole. Alternatively, after the incision is made and the hole drilled in the cranium, the device may first be inserted into the hole via the post. The surgeon may then lift the scalp or tissue into position over the device and then set the lifted tissue onto the attachment points.
In either case, the procedures may be accomplished by a variety of methods. One particularly useful tool may comprise a manipulatable handle having opposing grasping arms. The grasping arms may be used to secure and handle the device via the anchoring post. The tool may include a slidable block which may be angularly disposed relative to the handle so that the block may press down and secure a portion of the scalp or tissue to be lifted. The block is preferably disposed angularly such that the angle of the block is similar to the angle of the attachment points affixed to the brow lift device. Angling the block may allow the tissue to be optimally set against the attachment points and may provide the least resistance to piercing the scalp or tissue. Alternatively, the tool may omit the slidable block completely and the tissue may be set against the attachment points by other methods such as simply pressing against the tissue by hand.